Improved freeway analysis techniques: ramp and weaving operations for freeway lane model

Many recurring operational problems on freeways occur because of the turbulence caused by traffic entering the freeway and the presegregation of exiting traffic in the vicinity of ramps. This report proposes a method to estimate point flows at various locations immediately downstream of on-ramps and upstream of off-ramps in the right- most two freeway lanes. The point flows are computed from multi-variate linear regression equations using each origin destination flow and the length between ramp pairs as independent variables. Models have been developed for isolated on-ramps, isolated off-ramps, on-off ramps, on-on ramps, and an on-off-off ramp multiple weave site, all with four freeway lanes and an on-off ramp combination with three freeway lanes. All ramps are single lane with no auxiliary lanes. The equations are based on empirical data from seven California freeway sites with origin-destination flows and ramp spacings extrapolated using the microscopic freeway simulation model, INTRAS.